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HAZARD
Cherie Berry, Commissioner of Labor
1-800-625-2267 w www.nclabor.com
Excavation and trenching operations are among the most
hazardous of construction activities. OSHA defines an excavation
as any man-made cut, cavity, trench or depression in the earth’s
surface formed by earth removal. A trench is defined as a narrow
underground excavation that is deeper than it is wide, and is no
wider than 15 feet (4.6 meters), 1926.650(b).
Two excavation and trenching events in North Carolina resulted in
willful citations. In each case accident investigators determined that
employers had knowledge of the trenching excavation standard and
volatile conditions while employees worked inside unprotected
excavations. One event involved the installation of a 14-foot section
of PVC sewer pipe in a 12-foot deep excavation of Type B soil.
The other involved installation of a 10,000-gallon septic tank and
reactive tank in excavations up to 15.8 feet deep in Type C sandy
soil. The excavations in each event had nearly vertical walls with
no trench boxes or shoring to protect employees from exposure
to hazards.
One project was six to eight weeks behind schedule. Time
became of essence and safety was compromised, which resulted in
a cave-in causing blunt trauma and asphyxiation to an employee.
Cave-ins pose the greatest risk and are much more likely than
other excavation-related accidents to result in worker fatalities.
Other potential hazards include falls, falling loads, hazardous
atmospheres, and incidents involving mobile equipment. Trench
collapses cause dozens of fatalities and hundreds of injuries
each year.
Citations for these events included:
• Employees were not trained in the recognition of hazards.
• Daily inspections of excavations and adjacent areas were
not made by a competent person.
• No protective system was used for support of trench walls.
• Proper access and egress from excavation were not provided.
• Employees were not wearing personal protective equipment
such as hard hats.
• Work was performed in close proximity to overhead power lines.
• The spoil pile and equipment were too close to the excavation
and created a hazard.
Competent Person
OSHA standards require that trenches be inspected daily and
as conditions change by a competent person prior to worker entry to
ensure elimination of excavation hazards. A competent person is an
individual who is capable of identifying existing and predictable
hazards or a working condition that is hazardous, unsanitary or
dangerous to employees and who is authorized to take prompt
corrective measures to eliminate or control these hazards and
conditions. Presence and participation by a competent person can
prevent these common trenching hazards.
Protective Systems
There are different types of protective systems. Sloping involves
cutting back the trench wall at an angle inclined away from the
excavation. Shoring requires installing aluminum hydraulic or
other types of supports to prevent soil movement and cave-ins.
Shielding protects workers by using trench boxes or other types of
supports to prevent soil cave-ins. Designing a protective system
can be complex because you must consider many factors: soil
classification, depth of cut, water content of soil, changes due to
weather or climate, surcharge loads (e.g., spoil, other materials
to be used in the trench), and other operations in the vicinity.
Occupational Safety and Health Division
1101 Mail Service Center, Raleigh, NC 27699-1101
Dangers of Excavation and Trenching
The spoil pile and equipment were too close to the excavation and created
a hazard.
continued on page 2

HAZARD
Cherie Berry, Commissioner of Labor
1-800-625-2267 w www.nclabor.com
Excavation and trenching operations are among the most
hazardous of construction activities. OSHA defines an excavation
as any man-made cut, cavity, trench or depression in the earth’s
surface formed by earth removal. A trench is defined as a narrow
underground excavation that is deeper than it is wide, and is no
wider than 15 feet (4.6 meters), 1926.650(b).
Two excavation and trenching events in North Carolina resulted in
willful citations. In each case accident investigators determined that
employers had knowledge of the trenching excavation standard and
volatile conditions while employees worked inside unprotected
excavations. One event involved the installation of a 14-foot section
of PVC sewer pipe in a 12-foot deep excavation of Type B soil.
The other involved installation of a 10,000-gallon septic tank and
reactive tank in excavations up to 15.8 feet deep in Type C sandy
soil. The excavations in each event had nearly vertical walls with
no trench boxes or shoring to protect employees from exposure
to hazards.
One project was six to eight weeks behind schedule. Time
became of essence and safety was compromised, which resulted in
a cave-in causing blunt trauma and asphyxiation to an employee.
Cave-ins pose the greatest risk and are much more likely than
other excavation-related accidents to result in worker fatalities.
Other potential hazards include falls, falling loads, hazardous
atmospheres, and incidents involving mobile equipment. Trench
collapses cause dozens of fatalities and hundreds of injuries
each year.
Citations for these events included:
• Employees were not trained in the recognition of hazards.
• Daily inspections of excavations and adjacent areas were
not made by a competent person.
• No protective system was used for support of trench walls.
• Proper access and egress from excavation were not provided.
• Employees were not wearing personal protective equipment
such as hard hats.
• Work was performed in close proximity to overhead power lines.
• The spoil pile and equipment were too close to the excavation
and created a hazard.
Competent Person
OSHA standards require that trenches be inspected daily and
as conditions change by a competent person prior to worker entry to
ensure elimination of excavation hazards. A competent person is an
individual who is capable of identifying existing and predictable
hazards or a working condition that is hazardous, unsanitary or
dangerous to employees and who is authorized to take prompt
corrective measures to eliminate or control these hazards and
conditions. Presence and participation by a competent person can
prevent these common trenching hazards.
Protective Systems
There are different types of protective systems. Sloping involves
cutting back the trench wall at an angle inclined away from the
excavation. Shoring requires installing aluminum hydraulic or
other types of supports to prevent soil movement and cave-ins.
Shielding protects workers by using trench boxes or other types of
supports to prevent soil cave-ins. Designing a protective system
can be complex because you must consider many factors: soil
classification, depth of cut, water content of soil, changes due to
weather or climate, surcharge loads (e.g., spoil, other materials
to be used in the trench), and other operations in the vicinity.
Occupational Safety and Health Division
1101 Mail Service Center, Raleigh, NC 27699-1101
Dangers of Excavation and Trenching
The spoil pile and equipment were too close to the excavation and created
a hazard.
continued on page 2